#include <iostream>
#include <time.h>
int fibo(int n);

int fibo(int n)
{
    if (n == 1 || n == 2) return 1;
    return fibo(n-1) + fibo(n-2);
}
int main()
{
    using namespace std;
    int begin = clock();
    cout << fibo(50) << endl;
    int end = clock();
    cout << "using " << end - begin << endl;
    return 0;
}
// 1 1 2 3 5 8 13 21 